Maternal smoking is the most preventable cause of poor pregnancy outcomes in the United States. this study will provide useful information on potential mechanisms by which maternal smoking may contribute to SIDS, and may provide essential data for future work in detection and prevention of tobacco-related disturbances. This study utilizes a between-subject design to compare the effects of prenatal smoking on catecholamine response to hypoxia during delivery. Forty women will be identified as smokers or non-smoking (20 per group) at 28 weeks gestational visit.